Soldering terminal assembly and coil



c. E. WARREN ETAL soLDERING TERMINAL ASSEMBLY AND con;

Filed April 27. 19Go Aug. 25, `1964` United States Patent 3,146,419SOLDERING TERMINAL ASSEMBLY AND COIL Charles E. Warren and Charles F.McVoy, Jr., Danville,

Ill., assignors to General Electric Company, a corporation of New YorkFiled Apr. 27, 1960, Ser. No. 25,138 6 Claims. (Cl. 336-192) Thisinvention relates to coils for inductive devices and more particularlyto solder terminals used in conjunction with coils for inductivedevices.

.In the design of inductive devices, such as ballast transformers, it isfrequently necessary to provide suitable terminals for soldering thecoil leads and taps with other internal and external leads of theballast circuit. When the coil is a high voltage coil and thus woundwith line wire, the terminal used in conjunction with such a coil mustprovide a means for eifectively joining the extremely fine wire inelectrical contact with the larger sized wire used in connecting thevarious leads of a ballast circuit, such as the external leads connectedto the fluorescent la-mp and to the power source.

As thesize of the Wire forming an electrical coil decreases, itsmechanical strength decreases. Thus, it becomes 'important to provide acoil with a terminal to which all the connecting wires can be anchoredfirmly in f good electrical contact and to which soldered connectionscan be made without danger of burning the iine wire or the insulatingpaper. Further, such a terminal must be securely fastened to the coilbody so that the terminal can serve as a strain relief connection forthe line coil wire leads. In the event that one of the external leads isstrained, this strain should not be imparted to the line coil wire leadsbut should be taken up by the core and coil assembly which can bestwithstand the strain.

Coil assemblies generally used in inductive devices,

such as ballast transformers, are comprised of a pluralityof layers ofwire separated by a paper insulation interleaved between the layers ofwire. The outer periphery of the coil assembly is also made up of paperinsulation. Since design considerations require that the terminalassembly be attached to the outer periphery of the coil, it is desirablethat the terminal pads of the terminal assembly be fabricated of aresilient insulating material, such as paper, in order to prevent theterminal from cutting and tearing the outer protective covering ofthecoil assemblyn. For the same reason, it is also desirable that thepocket terminals, which are generally formed of a metal, be effectivelyseparated from the paper periphery of the coil by a resilient separatingmeans.

Further, in core constructions of the type used for ballast transformersit is desirable that the transverse dimensions of the coil be kept at aminimum. Therefore, when a terminal assembly is attached to the outerperiphery of a coil body, it should not appreciably increase thetransverse dimensions of the coil assembly. In a ballast appartus, thetransverse dimensions are critical because the ballast is generallyconcealed within a fixture. Fixture manufacturers require that thetransverse dimensions of 'a ballast be maintained under specifieddimensional limits. Since the terminal assembly must be necessarilyconnected to the outer periphery of the coil, preferably it should be sodisposed on the periphery of the coil so as to have only a minimaleffect on the transverse dimension.

` Cost considerations require that the terminal pads be preferablyfabricated of a low cost insulating material, such as paper. Further,from a standpoint of manufacturing costs, it is desirable thatit bepossible to solder all of the leads of the coil assemblies of aninductive device, such as aballast transformer, simultaneously in oneoperation which can be performed in a production line.

Accordingly, it is an object of the invention to provide an improvedcoil assembly having solder terminals in assembled relation therewithincorporating the desirable features set forth above.

Another object of the invention is to provide improved solder terminalswhich are adapted for connection to the outer periphery of a coil bodyand do not appreciably increase the transverse dimensions of a coilassembly.

It is a further object of the invention to provide an improved solderterminal for a coil assembly that will serve as a strain reliefconnection for fine coil wire leads connected therein.

A more specific object of the invention is to provide a terminalassembly that makes it possible to simultaneassembly having a terminalpad formed of two insulating layers defining a longitudinally extendingsection and a laterally extending section to which are attached aplurality of solder pocket terminals. The attaching portions of thepocket terminals are sandwiched between the two insulating layers sothat one of the layers effectively separates and insulates the attachingportion from the paper covering of the coil body. Preferably, eachpocket terminal is formed from a substantially rectangular elongatedstrip having two pairs of oppositely disposed outwardly extendingarcuate portions formed on the outer edges of the strip, the pocketbeing formed by bending the strip to bring the pairs of arcuate portionsin tangential relationship with each other. Also, the pocket terminal isformed with two oppositely disposed notches so that ne wire leads can behooked on one of the notches and wrapped around the smooth, roundedportion formed on the pocket terminal by the arcuate portions.

In another aspect of the invention, the two insulating layers of theterminal pad are formed from a single sheet, pieferably a paper sheet ofsuitable thickness, cut out so that the first substantially T-shapedlayer is formed as the second layer is formed by folding over two folderportions on the rst insulating layer to make-up a twolayeredsubstantially T-shaped terminal pad between which the attaching portionsof the pocket terminals are sandwiched.

The subject matter which we regard as our invention is set forth in theappended claims. The invention itself, however, together with furtherobjects and advantages thereof may be understood by referring to thefollowing description taken in connection with the accompanying drawingsin which:

FIG. l is a view of the terminal assembly in accordance with theinvention showing the insulating layers of the terminal pad unfolded;

FIG. 2 is a perspective view of a terminal assembly in accordance withthe invention showing one of the insulating layer folder portions foldedover and the other overlap portion partially folded over;

FIG. 3 is a top view of a pocket terminal illustrating how the terminalof the invention is formed from a metal strip;

FIG. 4 is a side View of the pocket terminal strip shown in FIG. 3;

FIG. 5 is a view in perspective, partially broken away,

illustrating the manner in which iine wire leads are wrapped around thepocket terminal;

FIG. 6 is a view in perspective, partially broken away, illustrating theimproved terminal assembly in a core mounted in a conventional ballastcore;

FIG. 7 is a perspective view illustrating how the pocket terminals ofthe invention as utilized in a ballast transformer are simultaneouslysoldered; and

FIG. 8 is a side view of a ballast apparatus having the case cut away toillustrate the interior disposition of the components after the ballastcomponents are removed from the fixture and soldering pot shown in FIG.7.

Referring now to the illustrated embodiment of the invention of FIG. 1,there is shown a terminal assembly y11 comprising a terminal pad 12, apair of folder portions 13, 14 and four pocket terminals 15a, 15b, 15C,15d having the attaching portions 16a, 1Gb, 16C, 16d and pocket portions17a, 1711, 17e, 17d, respectively. The folder portions 13, 14 are foldedabout the axes 18, 19 to form a second insulating layer.

lAs shown in FIG. 2, one of the folder portions 13- is folded over so asto sandwich the attaching portions 16a, 16b of the pocket terminals 15a,15b. The other folder portion 14 is partially unfolded -to illustratehow the two insulating layers of the invention are formed from a singlesheet. When the folder portion 14 is folded over, it will be in anabutting relationship with folder portion 13 and will overlay theattaching portions 16C, 16d of pocket terminals 15C, 15d.

In the hereinafter described exemplication of the invention, theterminal pad 12 'shown in FIGS. l and 2 was cut of from craft paper .015of an inch in thickness. It will be seen that when the folder portions13, 14 are bent to overlay the attaching portions 16a, 1611, 16C, 16d,they serve as a protective and insulating covering. When terminalassembly 11 is attached to a coil body, the folder portions 13, 14thereby prevent the sharp edges of the attaching portions 16a, 16h, 16C,V16a? from tearing the paper insulation of the coil body.

The pocket terminals 15a, 15b, 15C, 15d may be formed from a metallicstrip, such as tinned steel. In FIGS. 3 and 4, we have illustrated apocket terminal 15 before it is bent to form a pocket at a ninety degreeangle with Vthe attaching portion. It will be seen that the pocket-terminal strip 15 is formed with two pairs of outwardly extendingarcuate portions r21, 22 and 23, 24 formed in the side edges of thepocket terminal strip 15. Thus, a pocket is formed when the strip isbent along a transverse line intermediate the pairs of arcuate portions21, 22 and 23, 24 so that they are brought into tangential relationshipwith each other to form a pocket in which ythe stripped ends of externalleads and the coil leads are held in position before they are dipped insolder. A pair of notches 26, -27 are provided to facilitate bending ofpocket portion I7. An attaching portion 1-6 is formed with a point 28 tofasten the attaching portion 16 to the terminal pad 12. The pocketterminal 15 may be attached to the terminal pad 12 by bending the point28 after it has penetrated the terminal pad. It will be appreciated thata pocket terminal may be attached to a terminal pad by other fasteningmeans well known in the art.

The fragmentary view of FIG. illustrates how fine wire leads 29, 35 areatt-ached to a pocket terminal 15d. The line wire lead 29 is brought outfrom one side of a coil body 37. It will be seen that the fine wire lead29 is -iirst hooked in the notches 26d, 27d and then wrapped around thearcuate portions 21d, 22d, 23d, 24d which present a smooth, roundedsurface. Hooking the fine Wire lead 29 in the notches 26a', 27d resultsin the advantage that fine wire lead 29 is positioned against theterminal so that when the pocket terminal 15d is bent over on theterminal pad 11 after soldering, the fine wire 29 will not be ruptured.Y

Fine wire lead 35 is brought out from the front side of the coil, asseen in FIG. 5, and is hooked on notch 26C.

The fine wire lead is then wrapped around the arcuate portions 21C, 22C,23e, 24C. Thus, it will be appreclated that the fine wire leads 29, 35attached to the pocket terminals 15C, 15d are securely held in positionand the coil body 37 can be handled before soldering in a productionline type of operation Without disturbing the tine wire connections.

In FIG. 6, we have illustrated a perspective view show.- ing a brokenoff portion of a core and coil assembly 36 utilizing the terminalassembly 11 of the invention. The terminal assembly 11 is shown in xedassembled relation to coil body 37. The coil body 37 has a plurality oflayers of relatively ne wire. Interleaved between the layers of wire arelayers of paper 38. An external lead 39 and the tine Wire coil lead A29are shown connected in the soldered pocket portion 17d of pocketterminal 15d. A second external lead 41 and the fine wire coil lead 35are connected at the soldered pocket portion 17c of pocket 'Y terminal15C.

The coil body 37 and its wound wire layers are disposed about alongitudinal axis (not shown) on a laminated magnetic core assembly 42,the laminations of which are held together by a clamp 43. It will ybeseen that the terminal assembly 11 has a substantially T-shapedconfiguration presenting a longitudinal section 44 and a transversesection 45 on which the pocket terminals 15C, 15d are attached. A strap46 securely engages the longitudinal section 44 and serves to firmlyanchor the terminal assembly 11 against the outer periphery of the coilf o riphery of the coil body 37, if tearing of the paper is to beprevented. Thus, in accordance with the invention, the insulating layer31 is interposed between the attaching portions 16e, 16d of pocketterminals 15C, 15d and the periphery of the coil body 37. It will beseen that the pocket terminals as shown in FIG. 6 are dip 'soldered andare bent flat on top of insulating layer 32. By' bend-f ing the pocketterminals 15C, 15d and the others ove iii this manner, it will be seenthat the transverse dimensions of the coil body 37 are not appreciablyaffected. Moe= over, this feature results in the advantage that a sturdystrain relief connection is provided so that any external force exertedupon an external lead will not be transmitted to the fine wire leadslike the tap'29 brought out from the coil body 37.

In FIG. 7, we have shown an apparatus which illustrates how the terminalassemblies 11, '11 of the present invention make it possible to solderall connections of a core and coil assembly 36 simultaneously. For thepurpose of making the solder connections, a Yspecial fixture 47 isprovided with lead retaining springs 48, 219 to temporarily retain leads50a, 5017, 50c 50d, 50e, 5W, 50g, 59h firmly in position until theyaresoldered. A capacitor 51 is firmly held by the `x`ture 47 on top Vof a'core and coil assembly 36, such a's is commonly used in a fluorescentlamp ballast.

When the fixture 47, the capacitor 51-and the core and coil assembly areassembled in this manner, it is possible to readily position the leadsStirn-50h, 50c, Sild, 50e,

Silf, 50g, 'Stili in theirrespective pocket terminals 15a, 15b, 15C, 15dand the terminals of terminal assembly 11', which are not seen in theview of FIG. 7. .It will be seen that the core and coil assembly 36 hasa'pair of coils 37, 57, each coil having its termial assemblies .11, .11attached in assembled relation thereto, as is more clearly seen in theside view'of FIG. `8.

Referring again to FIG. 7, the entire assembly comprising the fixture,47, capacitor 51, and core and coil assembly 36 is positioned on a pairof-supports 53, 54 over a pot 55 containing solder 56. In thearrangement shown in FIG. 7, the solder contained in the individualmolds 60a, 60h, 60C, 60d is brought up to the pocket terminals 15a, 15b,15C, 15d by a vertically movable device 58 which may be mechanicallyactuated by a foot pedal or other means (not shown). Although thearrangement shown in FIG. 7 was found to be readily adaptable toproduction line operation, it will be appreciated that the terminalassemblies 11, 11 can also be soldered by lowering them into hot solder56.

After the various leads are soldered in their terminal pockets, theleads 50a, Sib, 50c, 50d, 50e, 50j, 50g, 50h are disengaged from theretaining springs 48, 49 and the fixture 47 is removed. The solderedpocket terminals 15a, 15b, 15e, 15d may then be bent fiat on the outerinsulating layer 32, as shown in FIG. 6. The capacitor 51 and core andcoil assembly are now ready for placement in a ballast case 60, as shownin FIG. 8. When placed in the case 60, the terminal assemblies 11, 11are on the top side of the coil bodies 37, 57. The capacitor 51 isdisposed within the case 60 in an end-to-end relationship with the coreand coil assembly 36.

Inv a ballast apparatus of the type illustrated in FIG. 8, thetransverse dimensions are critical because it is necessary to concealthe ballast in a fixture. Consequently, xture manufacturers imposelimitations on the transverse dimensions of the ballast case 60 which,of course, are determined by transverse dimensions of the componentscontained therein.

As shown in FIG. 8, the terminal assembly 11 is securely attached to theperiphery of the coil body 37 by two straps 46, 61. Similarly, theterminal assembly 11 of coil body 57 is attached by the coil straps62,63. A portion of one lead 34 is shown connected with the solderedpocket terminal 15d of terminal assembly 11 and also a portion of lead64 is shown connected in the pocket terminal 65 of terminal assembly 11.The two coil bodies 37, 57 are disposed on the center leg of the coreassembly 42 which is comprised of stacked laminations held together byclamps 43, 66. As is well known in the art, the coil and core assembly36-and the capacitor 51 are secured in the ballast case 60 by a suitablepotting compound, such as asphalt (not shown).

It will be appreciated that, as shown in FIG. 8, the thickness of theterminal assemblies 11, 11 are somewhat exaggerated. The actualthickness of the paper used in the practice of the invention was .015 ofan inch. The thickness of the tinned strip steel used to fabricate theterminal pockets 15a, 15b, 15C, 15d was .0l of an inch. Thus, theover-all transverse thickness of the pocket portion of terminal pockets15a, 15b, 15C, 15d was approximately .065 of an inch. It will be seen,therefore, that the terminal assemblies in accordance with the inventiondo not appreciably affect the over-all transverse dimensions of a coilbody.

In the foregoing described exemplification of the invention, we haveprovided a terminal assembly which can be readily fabricated frominexpensive parts and can be easily attached to a coil body. Although inthe illusf trative embodiment of this invention the terminal assembly isattached to the coil body by means of straps, it will be appreciatedthat the terminal pads can be attached to the coil body by means of glueor other suitable means.

The pocket terminal arrangement wherein the soldered pocket is bentflush with the terminal pad results in the advantage that the terminalserves as a strain relief type of connection for the purpose ofrelieving the fine core wire leads of any strains that might beinadvertently placed on the external leads. Further, the pockets formedby bringing the arcuate raised portions of the terminal strip intangential relationship with each other, make it possible to place allof the leads in position in the terminal pocket prior to soldering andto handle the assembly without disturbing the relative position of theleads.

It will be understood that while we have described above a particularembodiment of the invention, it will be apparent that many modificationsmay be made without departing from the principle of the invention. It isto be understood, therefore, that we intend by appended claims to coverall such changes and modifications that would fall within the truespirit and scope of the invention.

What we claim as new and desire to secure by Letters Patent of theUnited States is:

l. A coil assembly comprising a plurality of external leads, a coil bodyhaving a plurality of layers of wire wound with reference to alongitudinal axis, said coil body having coil leads brought out fromsaid coil body and having insulating material covering the outer layerof said body; a terminal pad having a first insulating layer and asecond insulating layer, said second insulating layer superimposed onsaid first insulating layer, said insulating layers defining a firstelongated section extending in the direction of said longitudinal axisand a second elongated section extending in a transverse direction; aplurality of solder pocket terminals, said pocket terminals having anattaching portion and a pocket portion, said external leads having endsthereof disposed in an axial direction in the pocket portions of saidpocket terminals and soldered therewith, said attaching portion beingfastened to one side of said first insulating layer on said secondelongated section thereof and said pocket portion folded over on theother side of said first insulating layer so as to overlie saidattaching portion; and means joining the superimposed insulating layersdefining said first elongated section and said terminal pad in a fixedassembled relation with said coil body, said attaching portion beingsandwiched between said first and second insulating layers and saidfirst insulating layer being interposed between said attaching portionand said outer layer of the coil body.

2. A coil assembly comprising a coil body having a plurality of layersof wires, said layers of wires having insulating material interleavedbetween said layers and covering the outer layer of said coil body; aterminal pad having a first insulating layer and a second insulatinglayer formed of two folder portions to define an axially extendingsection and a transversely extending section; a plurality of solderpocket terminals formed with an attaching portion and a pocket portionfor holding leads, said pocket terminals formed from a thin metal strip,each pocket terminal having two pairs of outwardly extending arcuateportions brought into tangential relationship by bending said stripthereby defining the pocket portion of the terminal, said attachingportion being fastened to the transversely extending section of saidfirst layer on one side and said pocket portion folded over on the otherside thereof so that said pocket portion overlies said attaching portionon the other side of said transversely extending section of said firstlayer to minimize the cross-sectional dimensions of the coil assembly; aplurality of external leads having their ends disposed in an axialdirection in the pocket portions of said solder pocket terminals andsoldered therewith, and means for strapping said axially extendingsection of the insulating layers to said coil body, said attachingportions of said plurality of solder pocket terminals being sandwichedbetween said first and second LayersE 3. A coil assembly comprising aplurality of external leads, a coil body having a plurality of layers ofWire, said coil body having coil leads brought out from said coil bodyand having insulating material covering the outer layer of said coilbody; a terminal pad formed of a first insulating layer and a secondinsulating layer superimposed thereon, said first and second insulatinglayers defining a substantially T-shaped configuration; a plurality ofsolder pocket terminals formed with an attaching portion and a pocketportion, said external leads having ends disposed in an axial directionin the pocket portions of said solder pocket terminals and solderedtherewith, said attaching portion being secured to said first insulating'layer on one side, said pocket portion folded over on the. other sideof said first insulating layer, and said attachingportion-'beingsandwiched Vbetween said rst yand second. kinsulatinglayers wherein said second layer is interposed between said attachingportion v'and said periphery of the coil body, and means for attachingsaid T-shaped insulating layers of said terminal pad in fixed assembledrelation with `said coil body so '-that the folded pocket portionsprovide a strain relief connection for leads soldered yinsaid pocketportion.

4. The coil assembly set forth in claim 3 in which said insulatinglayers are fabricated from a paper sheet cut out so .that the secondinsulatinglayer is superimposed on the rst insulating layer by foldingover two folder portions of the first insulating layer to form thesubstantially T- Vshaped configuration of the insulating layers.

5. A terminal assemblyfor attachment to a coil body and for connecting.the `coil leads with other leads, said assembly comprising: asubstantially T-shaped terminal layer, said second insulating layerformed by folding over a Irst and second folder portion to define theT-shaped configuration, said "rst and second folder portions and saidfirst insulating layer being fabricated from the same sheet ofinsulating material, a plurality-ofpocket terminals fastened to said'first layer. on one side of said first layer, eachof said .pocketterminals having an attaching portion and a pocket portion, saidattaching .portion being secured to .said first insulating layer ofvsaidterminal pad on one side of said rst insulating layer, saidpocketportion folded over the other side of said iirst insulating layer.to provide .a relatively iiat terminal assembly, said attaching`portion 'being sandwiched 'between said first and second insulatinglayers, andzsaid pluralityof pocket terminals formed from 20 pad havinga iirst insulating layer and a second insulating 5 a thin strip ofconductive material, each pocket terminal having two pairs of outwardlyextending arcuate portions brought into tangential. relationship bybending said strip `thereby forming said pocket-portion of theterminals.

6. A terminal vassembly vfor attachmentto a coil body and for connectingthe coilleads with external leads, said assembly comprising: a pluralityofi external leads, a terminalpadformed of'a first insulating layer anda second insulating layer superimposed thereon, said first Vand secondinsulating layersdening a substantially T- shaped configuration; av.plurality of'solder pocket terminals formed with an .attaching portionand a pocket portion, said attachingportion beingfsecured to said first'insulating layer on-one side, said'pocket portion folded over on theother `side of said iirstinsulating layer, said -solder pocket terminalsformed from a thin strip of conductive material, each solder pocketterminal having at least two pairs of outwardly extendingarcuate sideportions broughtoutinto tangential relationship by bend- -ing said stripto form saidpocket .portionQs'aid external leads having ends disposed inan axial .direction in the pocket portions and soldered thereto, `aplurality of coil leads `wrapped around'thepocket portions .and solderedthereto, and said .attaching rportion being sandwiched between said rstand second insulating layers whereby the 'folded pocket .portion of saidsolder pocketfterminals provide a strain relief connection for coilleadssoldered to said pocket portions.

References Cited in the ktile of this patent `UNITED.STATES PATENTS2,529,653 -Epstein Nov. 14, 1950 2,533,483 Lesquadro Dec. 12, 19502,631,184 Sampson a Mar. 10, '1.953 2,722,671 Zerwes Nov. 1, 19552,883,635V `Clark Apr. '21, 1959 2,992,370 Laviana July-11, 1961

1. A COIL ASSEMBLY COMPRISING A PLURALITY OF EXTERNAL LEADS, A COIL BODYHAVING A PLURALITY OF LAYERS OF WIRE WOUND WITH REFERENCE TO ALONGITUDINAL AXIS, SAID COIL BODY HAVING COIL LEADS BROUGHT OUT FROMSAID COIL BODY AND HAVING INSULATING MATERIAL COVERING THE OUTER LAYEROF SAID BODY; A TERMINAL PAD HAVING A FIRST INSULATING LAYER AND ASECOND INSULATING LAYER, SAID SECOND INSULATING LAYER SUPERIMPOSED ONSAID FIRST INSULATING LAYER, SAID INSULATING LAYERS DEFINING A FIRSTELONGATED SECTION EXTENDING IN THE DIRECTION OF SAID LONGITUDINAL AXISAND A SECOND ELONGATED SECTION EXTENDING IN A TRANSVERSE DIRECTION; APLURALITY OF SOLDER POCKET TERMINALS, SAID POCKET TERMINALS HAVING ANATTACHING PORTION AND A POCKET PORTION, SAID EXTERNAL LEADS HAVING ENDSTHEREOF DISPOSED IN AN AXIAL DIRECTION IN THE POCKET PORTIONS OF SAIDPOCKET TERMINALS AND SOLDERED THEREWITH, SAID ATTACHING PORTION BEINGFASTENED TO ONE SIDE OF SAID FIRST INSULATING LAYER ON SAID SECONDELONGATED SECTION THEREOF AND SAID POCKET PORTION FOLDED OVER ON THEOTHER SIDE OF SAID FIRS INSULATING LAYER SO AS TO OVERLIE SAID ATTACHINGPORTION; AND MEANS JOINING THE SUPERIMPOSED INSULATING LAYERS DEFININGSAID FIST ELONGATED SECTION AND SAID TERMINAL PAD IN A FIXED ASSEMBLEDRELATION WITH SAID COIL BODY, SAID ATTACHING PORTION BEING SANDWICHEDBETWEEN SAID FIRST AND SECOND INSULATING LAYERS AND SAID FIRSTINSULATING LAYER BEING INTERPOSED BETWEEN SAID ATTACHING PORTION ANDSAID OUTER LAYER OF THE COIL BODY.